Meanwhile, I think I will give my final rating. I have approximately played for around 20 hours which should be enough for a fair rating.
Gameworld & Story
This must be one of Crystal Dragons weakest points. Except for the background in the introduction of the game there is almost none reference whatsoever in the game of the actual story except a few parchments to guards that say they should lookout for intruders and that reinforcements are on the way etc. No other walltexts, books or dialogues bring any other light to this subject.
There are nothing to buy and no money to gain. After awhile you will have trouble carrying all items you´ve found and have to leave some.
NPC & Interactions
I haven´t met a single NPC yet so there are no RPG interactions.
Monsters and Tactics
There are very few different monsters. A new sort is introduced every second level or so. There are the guards, zombies, undead guards, flying skulls, hell hounds and beholders. They behave differently though. The hell hounds are very fast and attack at first sight and the zombies are much slower. Almost all monsters attack at first sight but guards and skeletons make morality checks from time to time and might try to flee the combat for a while. That is quite uncommon in this sort of game. Other than that, there are no tactics used by them whatsoever. They just head straight on. You use tactics like moving around them, hit them, move around, hit them etc and except for the very fast creatures, they are unable to counter that.
Some of them like the flying skulls shoots lightning bolts at you and the beholders can confuse you so you loose your orientation which makes you almost like a sitting duck. In that respect they are quite varied. You cannot use doors or pits against the monsters. Doors could not be closed on them and they will never step on pits unless they are flying creatures. Monsters could drop loot from time to time but it is either keys, food or parchments. I have never seen a weapon from a guard I believe.
The different levels are of different sizes. Corridors connects to rooms. Some rooms have labels that indicate if they are guard rooms, store rooms or whatever but other than that the map design feels more like built on puzzles and not on logic. I mean, what is the reason of several moving pits in a dungeon guarded by guards in the first place ? There is no realistic logic behind that. Each level is like a new puzzle that must be solved in order to progress. The automap feature is nice but it lacks indicators of where you have found buttons or illusionary walls. That would be very helpful.
Graphics, sound and interface
The graphics in the game is quite ok. It is solid and functional. It lacks smoother animation on monsters and it does not use the AGA-chipsets of the Amiga which is too bad. For a game in 1994 it should have been able to muster better graphics or at least higher resolution. Black Crypt and Eye of the Beholder has better or more varied graphics.
The title music and character generation music is very very good. So good in fact that I´ve been listening to it for the past 10 years without even playing the game. In the game there is no music whatsoever and very sparse sound effects. You can hear doors, clicks, weapon slashes and magic but there are no environmental sound at all.
Interface is clean and functional. Items are stored in bags or chests. It is too bad you don´t have hotkeys for certain spells. To switch spells during combat is not recommended.
I had a lot of fun with Crystal Dragon in the beginning but just after a few levels I was tired of the huge amount of puzzles that kept you from progressing. There is always a key hidden somewhere that has to be found, there are always a few buttons and illusionary walls that must be found to be able to progress on each level. The game is too hard. Even though I had the help of a translated german walkthrough when I got really stuck.
It would be better if they reduced the amount of obstacles and made a few ones tougher. Now you never feel you progress into the game in a satisfactory way. There are never alternative ways to solve anything. You must do it right or get stuck. You cannot win by just combat the monsters.
The combat is ok, the magic system works well, as well as the inventory. You find a few items along the way. Not as much as in Eye of the Beholder series but enough to keep you looking for more. When you progress it feels very good but too soon you are stuck again. Food and water is a constant problem and you could easily starve to death if you are not cautious. You have to survive of hunting rats in the later stages.
This game could have been done better. As pure entertainment it is worse than Black Crypt and Eye of the Beholder. Still, if you haven´t played this game and played all the others and you think they were too easy, this will really be a challenge. Just make sure you have a lot of sparetime.
It is however more entertaining than Dragon Wars and Bard´s Tale III. Perhaps the major problem with this title is the lack of help on the internet when getting stuck. With more than one walkthrough I would surely continue with this game.
If I ever found the solution to my puzzle on level 9 I might very well continue I just don´t think that will happen.
Walkthrough to level 7
Complete walkthrough translated from german
[Added 2012-07-07] Complete walkthrough with maps. Translate to english.
[Updated 22 october]
I actually managed to solve the puzzle by looking for the original german walkthrough and do a retranslate of it. Now I am down two levels further at level 11 but am stuck again trying to defeat the evil sorceress Elitia which seems invulnerable to all my weapons and spells. After possibly having inflicted over 5.000 points of damage on her I fear she is regenerating herself every 20 seconds or so.